The present invention relates to an antenna, and in particular to a dual band antenna having a bending structure which is adapted for a wireless communication device.
There is a growing need for dual band antennas for use in wireless communication devices to adapt the devices for dual band operation. For example, the transition of application frequency from 2.45 GHz (IEEE802.11b) to 5.25 GHz (IEEE802.11a) requires an antenna which operates at both frequencies, rather than two single band antennas. Referring to FIG. 7, Finnish patent application FI-982366 discloses a planar inverted-F antenna (PIFA) radiating element 600 defining a non-conductive slot 601-602-603 which divides the planar radiating element into a first branch located within a second branch. A feed point 604 and a ground contact 605 are located close to the inner end of the slot. The first branch and the second branch constitute two adjacent PIFA radiating elements on one and the same planar surface and in the vicinity of one and the same ground plane 606. The patent application also discloses that the first branch is the higher frequency element, and the second branch is the lower frequency element.
However, this substantially planar structure make the dual band antenna unsuitable for installation in a space having an irregular shape, such as is found in a laptop computer.
Hence, an improved antenna is desired to overcome the above-mentioned shortcomings of existing antennas.
A primary object, therefore, of the present invention is to provide an improved dual band antenna with a bending structure and reduced dimensions which is adapted to fit in a space having an irregular shape.
A dual band antenna in accordance with the present invention comprises a ground patch having a connecting portion and a bending portion, a first radiating branch transversely extending from the connecting portion, and a second radiating branch partly surrounding the first radiating branch and including a connecting patch extending from the connecting portion and a radiating patch extending from the connecting patch. The connecting portion, the first radiating branch and the connecting patch are located in a same first plane. The bending portion and the radiating patch are respectively in separate planes making predetermined angles with the first plane to form a bending structure adapted for an irregular installation space in an electronic device.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the accompanying drawings.